Vinylidene chloride compositions



Patented July 22, 1941 2,249,918 vmnmsmz cnnoamn comosrrrons Robert C. Reinhardt and John H.

Reilly, Midland,

Micln, assignors to The Dow Chemical Company, Midland, Mich a corporation oi Michigan No Drawing.

Original application November 16, 1938, Serial No. 240,861.

Divided and this application November 28, 1940, Serial No. 307,576

4 Claims. (Cl. 28032) This invention relates to useful liquid dispersions or solutions of polymerized and co-polymerized vinylidene chloride.

The problem of preparing solutions or disper-. sions (herein referred to simply as solutions) of vinylidene chloride polymers and co-polymers is rendered difllcult by the fact that such of the said polymeric bodies as dissolve readily in many of the common solvents are either too unstable or too low melting to be generally useful or desirable as ingredients of surface-coating compositions, and the like. The converse is also true, i. e., the vinylidene chloride polymeric products which are sufiiciently stable, and which have high enough softening points to be otherwise acceptable as plastics, are insoluble in the ,usual solvents, such as chloroform, carbon bisulflde, ethylene bromide, or benzene, even at boiling temperature, and are only sparingly soluble in tetrachioroethane.

The polymer of pure vinylidene chloride (monomer boils at 3l.532 C.) which is insoluble in the above-named solvents, has a softening point at or above 170 (3., is stable at temperatures of about 210 C., or higher, and is substantially unchanged in composition when heated in a glass container at 180 C. The co-polymers, whose softening points are above 130 C., are prepared by polymerizing pure monomeric vinylidene chloride with a minor proportion of vinyl chloride, vinyl or other unsaturated esters or carboxylic acids, esters of acrylic or methacrylic acids, or styrene, and the like. These co-polymers are also insoluble in the solvents named above and are stable at temperatures at least degrees above their respective softening points. The copolymers having best properties for surfacecoating, film-, thread-, or filament-forming, and similar purposes, are those wherein the co-polymerized ingredient contains only one active ethylenic group. By the expression active ethylenic group is meant a canbon-to-carbon double bond, whichenters into the co-polymeric structure under the polymerization conditions employed. In 'order to utilize these co-polymers for the specific purposes, however, it is necessary that solutions of the same be made available.

It is among the objects of the invention to provide solutions or dispersions comprising the polymer of pure vinylidene chloride (boiling point 3l.5-32 C.) and/or high-softening co-polymers thereof with co-polymerizable compounds containing only one active ethylenic group, which are suitable for use in the preparation of lacquers, films, threads, filaments and the said polymer or co-polymer.

We have now found that the polymer of pure vinylidene chloride and the high-softening copolymers wherein the co-polymerlzed ingredient contains only one active ethylenic group, although substantially insoluble in boiling chloroform, carbon bisulflde, ethylene bromide or benzene, may be .made to form clear dispersions or solutions in certain selected solvents, which are useful-in the preparation of lacquers, films and filaments, etc. The solvents which we have found satisfactory for this purpose are nonpolar liquids boiling above C., examples of which are the liquid polychlorinated aromatic hydrocarbons, the liquid (aliphatic, alicyclic, and alkyl-aryl) ketones, and the (open-chain and cyclic) aliphatic ethers. Suitable polychlorinated hydrocarbons are: ortho-dichlorobenzene, trichlorobenzene, ethyl-dichlorobenzene, and the like. The useful ketones boiling above 100 C. include methyl-isobutyl-ketone, mesityl oxide, cyclohexanone, heptanone-2, acetophenone, etc. Ethers which are useful include dichloro-diethyl ether, lA-dioxane, 1.3 dioxane, and similar aliphatic ethers, boiling above 100 C.

The solutions are prepared by heating the polymer or co-polymer with one or a mixture of the solvents of the previously named classes. Many of the solvents named, including orthodichlorobenzene and trichlorobenzene, retain the polymer in clear solution only at temperatures above 0., below which temperature the composition becomes a gel. Hence, when the boiling point of the solvent employed permits of such temperatures, 140 C. is a good temperature at which to prepare solutions. In all cases when the polymer or co-polymer is dissolved or dispersed in a solvent of the class named, the resulting dispersion while hot has the appearance of a true solution. When cooled, however, it may in some cases take on the appearance of a colloidal gel. If desired, plasticizers may be added to the solutions.

The following are embodying the invention:

powders of Example 1 The polymer of pure vinylidene chloride (20 grams) is heated with trichlorobenzene (100 cc.) to a temperature of about -170 C. The polymer dissolves in the trichlorobenzene, and remains in clear solution at temperatures above 143 C. Clear tough flexible films are formed by examples of compositions tough and rubbery,

70 per cent vinylidene'chloride and 30 per cent vinyl acetate is dissolved in 80 grams of 1.4-dioxane, by warming.

Example 3 A per cent solution in dioxane was prepared from a high-softening co-polymer of '10 per cent vinylidene chloride and 30 per cent vinyl chloride, and to the solution was added 1 per cent of diphenyl-monorthoxenyl phosphate as a plasticizer. The solution was spread on a glass plate from a standard film caster and was dried in a film drier at 50 C. The foil produced was about 0.0005 inch thick, nearly transparent, very and quite insoluble in organic solvents at room temperature. It could be redissolved readily in dioxane, cyclohexanone; or mesityl oxide by heating.

Example 4 In a manner similar to Example 3, films were made from high-softening co-polymers of vinylidene chloride with ethyl acrylate, methyl methacrylate and styrene, respectively, employing cyclohexanone as the solvent.

The following table illustrates the preparation of lacquers from vinylidene'chlorlde co-polymers.

Anumber of co-polymers were dissolved to form 5 per cent solutions in dioxane. The dilution ratio of the dioxane solutions with various lacquer solvents and thinners was determined, and it was found that substantial volumes of lacquer diluents could be added, while still'retaining the copolymer in solution.

Lacquer films deposited from such solutions have no visible crystal structure whenexamined under a microscope at 900x magnification. The

films are tough, fire-resistant, excellent dielectrics, and are not attacked by acids, alkalies,

. salts, polar organic solvents, or by most non-polar solvents at ordinary temperatures.

The herein described solutions of the polymer of pure vinylidene chloride and of the high-softening co-polymers thereof are adapted to the preparation of surface-coating compositions and for making of foils, filaments, molding powders and the like in known manner. When the solution is to be employed at low temperature, such solvents as dioxane, cyclohexanone, acetophenone, heptanone-2, methyl-isobutyl-ketone, and the like, or mixtures thereof, are satisfactory. If

, the solutions are employed at high temperatures as, for example, in the casting of films, trichlorobenzene and ortho-dichiorobenzene are preferred solvents.

This application is a division of our co-pending application, Serial No. 240,661, filed November 16, 1938, which, in turn; is a continuation-inpart of our earlier application, Serial No. 151,182, filed June 30, 1937.

1. A composition of matter comprising (1) a polymeric material which is insoluble in chloroform, carbon bisulfide, ethylene bromide, and benzene, said material having a softening point above 130 C., being thermo-stable at least to its softening point, and being selected from the group consisting of the polymer of pure vinylidene chloride and co-polymer's thereof containing only a "minor proportion of a co-polymerized ingredient having only one active ethylenic softening point, and being selected from the grouprconsisting of the polymer of pure vinylidene chloride and co-polymers thereof containing only a minor proportion of a co-polyinerized ingredient having only one active ethylenic group, completely dispersed to form a solution in (2) trichlor'obenzene, which solution remains clear at temperatures above about 140 C., and forms gels at lower temperatures.

3. A composition of matter comprising (1) a polymeric material which is insoluble in chloroform, carbon bisulfide, ethylene bromide, and

- benzene, said material having a softening point above130 C., being thermo-stable at least to its softening point, and being selected from the group consisting of the polymer of pure vinylidene chloride and co-polymers thereof containing only a minor proportion of aco-polymerized ingredient having only oneactive ethylenic group, completely dispersed to form a solution in (2) ortho-dichlorobenzene, which solution remains clearat temperatures above about 140 C., and forms gels at lower temperatures.

4. A composition of matter comprising (1) a polymeric material which is insoluble in chloroform, carbon bisulfide, ethylene bromide, and benzene, said material having a softening point above C., being thermo-stable at least to its softening point, and being selected from the group consisting of the polymer of pure vinylidene chloride and co-polymers thereof containing only a minor proportion of a co-polymerlzed ingredient having only one active ethylenio group, completely dispersed to form a solution in (2) ethyl-dichlorobenzene, which solution remains clear at temperatures above C., and forms gels at lower temperatures.

4 ROBERT c. REINHARD'I.

JOHN H. REILLY. 

